Maybe you've thought about how to get rid of them, but haven't done it yet? (they're called "Snap Previews...")
There are a few ways to make them gone. If you just add shots.snap.com to your AdBlock (or your /etc/hosts file), then that'll solve the problem.
Another alternative is politely asking them to not pop up; you can set an option by clicking the little "gear" icon when the window does come up. That'll store your preference in a cookie for who-knows how long.
I just put this line in my /etc/hosts, though.