What causes your bones to make a popping sound?

Popping of the chest is caused by the cavitation of the ribbones connection to the sternum. The sternum is the large bone section at the front center of the ribcage structure. Along either side of the sternum the coastal cartilage (plural) connect the rib and the sternum. Where these connections meet the sternum are joints similar to those of the rest of the body. At these points (as in your fingers) your bones can pop or undergo cavitation (the rupturing of separated of gas bubbles mixed into fluids, resulting in the popping sound).