Facebook recently changed the way you view photos. By default, when you click on a photo, the photo pop ups over the Facebook page. Previously, when you clicked on a photo, you would be directed to another Facebook page with the photo displayed on the page and previous and next links above the photo.
If you preferred the old way Facebook displayed photos, do the following:
Right Click on the picture.
Select Open link in new tab with the left mouse button.
That is it, you can now view photos without the pop up.