You can do something like this..

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">Popup image</button>

<div id="myModal" class="modal fade" tabindex="-1" role="dialog">
  <div class="modal-dialog">
    <div class="modal-content">
        <div class="modal-body">
            <img src="//placehold.it/1000x600" class="img-responsive">
        </div>
    </div>
  </div>
</div>

Demo: http://www.bootply.com/123443

You can try this code if you are using bootstrap 3:

HTML

<a href="#" id="pop">
    <img id="imageresource" src="http://patyshibuya.com.br/wp-content/uploads/2014/04/04.jpg" style="width: 400px; height: 264px;">
    Click to Enlarge
</a>
    
<!-- Creates the bootstrap modal where the image will appear -->
<div class="modal fade" id="imagemodal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span><span class="sr-only">Close</span></button>
        <h4 class="modal-title" id="myModalLabel">Image preview</h4>
      </div>
      <div class="modal-body">
        <img src="" id="imagepreview" style="width: 400px; height: 264px;" >
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
      </div>
    </div>
  </div>
</div>

JavaScript:

$("#pop").on("click", function() {
   $('#imagepreview').attr('src', $('#imageresource').attr('src')); // here asign the image to the modal when the user click the enlarge link
   $('#imagemodal').modal('show'); // imagemodal is the id attribute assigned to the bootstrap modal, then i use the show function
});

This is the working fiddle.

You can do something like this..

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">Popup image</button>

<div id="myModal" class="modal fade" tabindex="-1" role="dialog">
  <div class="modal-dialog">
    <div class="modal-content">
        <div class="modal-body">
            <img src="//placehold.it/1000x600" class="img-responsive">
        </div>
    </div>
  </div>
</div>

Demo: http://www.bootply.com/123443

You are very close to your goal, you have 2 images

<img height="100" width="80" id="1" data-toggle="modal" data-target="#myModal" src='http://tympanus.net/Tutorials/CaptionHoverEffects/images/1.png' alt='Text dollar code part one.' />
<img height="100" width="80" id="2" data-toggle="modal" data-target="#myModal" src='http://tympanus.net/Tutorials/CaptionHoverEffects/images/2.png' alt='Text dollar code part one.' />

One Modal

<div id="myModal" class="modal fade" role="dialog">
    <div class="modal-dialog">
        <div class="modal-content">
            <div class="modal-body">
                <img class="img-responsive" src="" />
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
            </div>
        </div>
    </div>
</div>

If you want to show image in modal with your approach using click function

$(document).ready(function () {
    $('img').on('click', function () {
        var image = $(this).attr('src');
        $('#myModal').on('show.bs.modal', function () {
            $(".img-responsive").attr("src", image);
        });
    });
});

Fiddle

Or you can use bootstrap modal event function only, less complicated and better approach (recommended solution)

$(document).ready(function () {
        $('#myModal').on('show.bs.modal', function (e) {
            var image = $(e.relatedTarget).attr('src');
            $(".img-responsive").attr("src", image);
        });
});

Fiddle