Weird pop when backing up with the wheel cut.

[Terry Church]

I have a 2001 Chevy S10 4x4, I love it, however, recently I have replaced the following items: New front hubs and bearings, both front cv axles, new upper control arms, upper and lower ball joints, new vacuum actuator and cables and switches, new inner and outer tie rods, new idler arm, new pitman arm. Today while backing out of a parking spot with the wheel cut it made a loud pop noise and sounded as if something was bound up the popped loose, then it did it again after I had backed up and shut it off got out and was walking across the parking lot "POP". It only does it when the wheel is turned not backing up in a straight line. Anybody know what this might be? Any feedback will be helpful.