Internet (and Smartphone) Streaming Radio: What's With Not Playing the Whole Song?

I’ve used iHeart Radio, Raditaz Radio, and am currently using Jango. In all three apps I’ve noticed that about one in ten songs will end prematurely. Sometimes it’s maybe 20 seconds into the song; other times it’s much deeper into the song. Nevertheless, the song will end out of nowhere and go to the next one.

What is this about? I assume it has something to do with royalties?

One bump. No one knows??

I started having this happen on every song on Pandora. I logged out, cleared cookies and cache, and when logged back in, everything was back to normal.