Hi mate its bursitis, my left shoulder clicks/makes popping noises from time to time, had it get a ultrasound and found mild thickening of the bursa, which is bursitis/mild impingement. the popping is pretty much a small impingement and the joint moves and gets caught on impingement and clicks. go to doc and either get a cortisone shot/take natural anti inflams/creams on it. mines 100% healed now.