Exploding Soup

While heating some soup in the microwave oven, precisely as instructed on the can, the soup made several loud popping noises and splattered itself all over the inside of the microwave oven. I’ve read about superheated water, but soup has plenty of nucleation points. My guess is that the thickness of the soup prevented convection currents from distributing the heat, leading to hot spots that formed explosive steam bubbles. That still doesn’t explain why the bubbles were so violent. Does anyone have an explanation?