Here you go. The reason I suggested rotating the springs was as you can see in my pics, the spring is not compressed perfectly up and down. The thought was maybe the way the spring was compressing two of the coils were coming together.
Another thought, is there any chance your shocks are binding somewhere through their stroke? I know my shocks have a spherical upper mount to help them articulate better. Maybe yours are just sticking and the pop is when they release.
By the way you owe me one now. Laying on a cold concrete floor in ~20° weather sucks.