When lighting strikes it causes a cavity or vacuum in the air the loud noise is caused by the vacuum collapsing. as an example popping a plastic bag cause the same effect.
The loud rumbling noise after a lightning flash is called thunder.
It is the alternator....
The fuel in the cylinders exploding
Wheel bearing
A little kid in the trunk with a hammer
Noise is a movement of the air. An explosion is a rapid expansion of gasses, which causes movement of the air.
Agressive tread, bad alignment
loose belts
I think it's called an engine
A loud thud noise in the rear brakes might be caused by stuck calipers or by brake drums that are out of round. You might also have uneven wear on the brake pads.
bearing
rack and pinion