Fireballs, unlike creepers, don't appear to have a cap of ExplosionPower. Exploding the fireball with the ExplosionPower of any huge number below integer limit (example: 999999999) will make the game freeze trying to calculate the explosion. Mobs will not move, chunks stop loading, saving the world doesn't work. 

The bug

1) /summon fireball ~ ~ ~ {ExplosionPower:999999999}

2) Make it fly into the ground by punching it

3) Game freezes