Answer by Bart Loews:

What happens when you pop a joint is that nitrogen, oxygen, and carbon dioxide rush out of the joint. 

There was a single study from the 50s that showed that it could cause damage over the years and lead to swelling of hands and decreased grip strength when you pop your knuckles, but no follow up has been performed to confirm the results.

Anecdotally, this man cracked one hand every day for 60 years while not cracking the other and had no change between them., the noise and feeling can be from tendons snapping back into place over a joint.  This can be painful, but therapeutic in the long run.

Here's an MRI of a finger joint popping:

What causes the noise when you crack a joint?
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What Happens When You Pop Your Back?

Finally, no, it won't stunt your growth. Pretty much the best way to do that is to not eat properly.

Is it bad to always crack my back joints? And will it also stunt my growth if I keep doing it?