Curious Owl- WHY BALLOONS BURST SO LOUDLY?

two reasons
1. the sudden release of pressure inside the balloon causes fluid (gas or liquid) to expand suddenly. This sudden and at once collision of high pressure fluid with its surrounding atmospheric pressure causes the sound.
2. Sudden rupture of a streched material like rubber contributes to the sound.
This video contains step by step videos to enhance the understanding behind the phenomenon. Some mind blowing slow motion videos are also there. I personally love the water balloon bursting slow motion video.

thanks for watching.