¿Qué pasa cuando crujimos los nudillos?

The video explains the phenomenon of knuckle cracking, where a noise is produced due to the formation and bursting of a gas bubble in the space between bones. Scientists are unsure why the sound is so loud. The bubble dissolves back to normal within half an hour. Frequent knuckle cracking can lead to joint inflammation and a reduction in grip strength.

Why do scientists not know why the sound of knuckle cracking is so loud?

What happens to the gas bubble after it bursts?