“Is the popping sound in my left hip caused possibly from sitting down too much?”

Snapping at the hip usually comes about due to inflammation of the bursa over the hip area. You can also see it occur due to the iliotibial band. Snapping in the groin area may be due to a labral tear, psoas tendinitis or early arthritic changes. If this is becoming more progressive in particular if it’s becoming more painful you should be evaluated by an orthopedic surgeon before significant damage may occur. Good luck

It is most likely greater trochanteric bursitis. Yes, sitting can make it happen. Look up stretching exercises for this. It will not make your hip "lock."

WAW