* Overinflation: When a balloon is overinflated, the rubber stretches to the point where it can no longer support the pressure and pops.
* Temperature changes: If a balloon is filled with air at a higher temperature than the surrounding air, the air inside the balloon will expand as it cools down, causing the balloon to pop.
* Puncture: If a balloon is punctured, the air inside the balloon will escape and the balloon will deflate.
In general, balloons are more likely to pop when they are made of thin rubber, underinflated, or exposed to sharp objects.