This seems to be a recent addition to Google Image Search's tablet interface. When you tap an image, Google maximizes it and hides the details placed at the bottom of the page. The nice thing is that you can continue to check the other image search results using the maximized mode.
I've only tested this feature on an iPad, but it should also work on an Android tablet. Hopefully, Google will add this great interface to the desktop. Speaking of feature requests, Google should let you open image search results in a new tab when you use the tablet interface.