After my recent track event on the ride home I noticed this pop sound coming from the left rear hub / suspension area. I noticed in stop & go traffic. I would leave the car in gear and after decelerating it would happen after applying throttle. Initial searching suggests rear axel nut may need tightening. The concerning thing is I just tightened the thing before I left for the track event. The nut on this side of the car had definitely loosened.

Video for reference...