The hip is a complex joint that takes enormous daily strain. If your pelvis is tilted, then one hip starts to take extra loading, eventually causing severe pain from the overuse/ misuse of the tendons and musculature. Your body recovers a bit with rest, but then the process starts all over. Bursa are often irritated and become inflamed.
What you may be experiencing (ie the 'popping'), may be the ileopsoas tendon 'snapping' as it moves over bone.
Of course scoliosis may be a symptom, rather than a cause. (Are you sure your legs are exactly the same length? That might sound a dumb question...but many people's legs are not, for one reason or another, and the simple answer to the pain issue is a shoe-lift!! - so correcting the pelvic tilt, and easing the back pain). You need expert assessment by a physio.