I have the same popping noise coming from the right side. I raised the vehicle, removed the tire/wheel and had a friend move the steering wheel back and forth. The noise is from the upper spring mount and seat. I went to the dealer today and the wanted me to leave the car for a couple of days to disassemble and inspect the spring mount and order parts to repair. Parts and labor $363, if strut assembly and mount were needed. $240 if mount only, (out of warranty) . I'll get a new mount from Rock Auto for $30 and do it myself.