What causes the tingling/shivering sensation down your back/spine when you listen to music?

I hope some other people understand what I mean when I say this.

This happens a lot to me when I listen to a truely epic song (Octavarium by Dream Theater for example), or watching an awesome movie. However it also happens when I make a leap of logic to understand something that was previously hidden or “revolutionary” in my thinkings.

Does anyone else get this? If so, under what conditions? Also if anyone has any explanation for this effect, shoot away with it. I’m pretty sure i’ll get the shivers after reading it :D