I’ve had patients tell me of other kinds of popping and “ripping” that occurs suddenly, with pain and subsequent swelling and bruising. This is probably scar tissue tearing, and depending on the situation it can be beneficial or problematic.
The “clunk” sound is an interesting phenomenon. This is often felt as a shift, which may or may not accompany the louder pop. It’s often described as distinct from the “regular pop” that people describe, but it actually may be the same phenomenon, just louder and more noticeable.
It might be a true subluxation, in which the joint is off axis, and a particular movement shifts it back on axis. If this is true, than these sounds occur in what I would classify as unstable joints and the ones most in need of exercise training to strengthen and improve motor control.
This happens often in people that have training-related-injuries, repeated injuries in one area, or long-term chronic issues.