Joints make a popping noise because of gases escaping, rough surfaces and movement, according to the Library of Congress Science Reference Services. Joints can also make cracking, snapping or grinding sounds.Continue Reading
Joints are surrounded by synovial fluid, which acts as a lubricant, states Science Reference Services. This fluid contains nitrogen, oxygen and carbon dioxide, and when the joint is cracked or popped, the joint capsule is stretched, causing the rapid release of gases and the "popping" sound.
Simple movement of joints that cause them to temporarily move slightly out of place also causes a popping sound when the joint returns to its original position, according to Johns Hopkins Department of Orthopedic Surgery. Joints afflicted with arthritis lack lubrication and may make popping noises as the roughened joints rub together.Learn more about Human Anatomy