Generally speaking, non-painful pops are not concerning and may be normal. Pops may happen for many different reasons. Crepitus is a sound that joints can make that is from cartilage on bone or can be bone on bone. This can be painful or non-painful. When painful this can be indication of arthritic changes. Other pops can come from nerves or tendons moving over bony structures. Example of this can is the ulnar nerve on the inside of the elbow. This can be problematic if numbness and/or tingling or pain into the pinky and ring finger occurs.
Injuries of the labrum can cause popping. Labrum can be found in the hip and shoulder. It is a soft tissue structure that deepens the socket and proves some stability. Usually, a normal labrum would not cause popping, unless the head of the ball of the joint is not well controlled with movement.
Injuries of the meniscus also can cause popping. This is a similar structure to the labrum and has similar function but is found in the knee. The knee is a hinge joint, however there is no socket like the hip. Cushion and support are important functions of the meniscus. Not all tears of the meniscus will produce popping but type and location, among other factors are most likely to determine if popping will occur.
If you have a painful joint consider a medical, physical therapy, or chiropractic evaluation. Popping with pain should be evaluated and may need treatment.