Reason why bones seem to crack???????

Answer 1

The sound you hear is known as Articular release, which is a physiologic event that may or may not be audible. It is seen in patients with healthy joints as well as those with somatic dysfunction.

Articular release is a repeatable phenomenon that can occur with or without an accompanying noise. It causes a freeing of motion and a release of joint tension.

However, the physiologic and anatomic explanation for what
happens during articular release is not fully understood. What is known is that articular release occurs when joint motion extends past the physiologic barrier. This extension may be accomplished by an outside force—as induced by a physician—or through muscle movement not directly emanating from joint release. The sound, or the noise,is what people notice in articular release; the subjective relief it provides is secondary.

In other words it is not a serious problem. I've enclosed a link to a website where you can find out more about this condition.