Check your steering stops on each side and see if they are badly bent or broken off. I have same problem and I believe that the steering is binding becus it is allowed to steer to sharp. Both of mine are bent right over and when I turn to tight where as the steering wheel cant go any farther, that's when I get the poping sound is when I start to straighten out the wheel. Not sure if it's in the gear box or on the driver side spindle where the cross steer occurs. I need to make new stops, I can allmost do a U-Turn on a city sidewalk...lol.
Could be bushings,,,,,,if you don't see anything obvious, like the sway bar, kingpin or spring bushings,,,,,take the one side of the shocks off and see if the noise goes away,,,,