A sonic boom occurs when an object moves through a medium at the speed of sound in that medium. Due to the Doppler Effect, the sound waves will stack on top of each other, adding together (constructive interference) to create a sound wave with a very large amplitude.
If a jet plane is traveling faster than Mach 1.0, why can people in the front of the plane still hear the sound of the engines in the back of the plane?
Sonic Booms & Jets – Best Compilation (3:26 – watch first 1:42 only)
Going Supersonic – Insane F-18 Sonic Boom Past An Aircraft Carrier! (0:58 – watch from 0:38)
F-35 performs the best sonic boom (8:04 – watch from 3:30 to 3:55, and 4:25 to 4:55)