Is "going to pop" common expression? Is it only used in song?
"Pop" in this context is a synonym for "burst" or "explode". The phrase "going to pop" can be used in many contexts where something "bursts" or "explodes". However, "pop" usually describes things that burst because of too much air pressure. Ex: The balloons are going to pop if you put them on the glass! Ex: My tire pressure is low, I'm worried that they're going to pop.