Question

What causes loud sound when popping a baloon/bubble?

Answer 1

Let's use the balloon as an example. When you inflate it the contents are under pressure because the latex wants to shrink back to its natural size. When you pop the balloon that pressure is released. It rushes outward temporarily creating a void. The void then sucks in the surrounding air. The popping sound is the air molecules slamming into each otherwhen the void is filled.

Answer 2

The air in a balloon is at a higher pressure than its surroundings because the elastic tension of theballoon skin is pulling inwards. ... The high-pressure air that was inside theballoon is now free to expand and this creates a pressure wave that our ears hear as a bang.