Popping while turning is a classic sign of a bad outer CV axle joint. A "constant velocity" joint is the flexible bit in the axle that allows it to move up and down with the suspension, or pivot when you turn the wheel. The inner CV joint closest to the transmission or differential deals primarily with up-and-down suspension movement. The outer joint, close to the hub, has to deal with both up-and-down movement, and the pivoting steering hub on top of it.
When the outer joint wears out or breaks, the mechanism will constantly bind up, jam and release. This bind-and-release cycle causes the popping sound. It's not impossible for a badly broken inner CV joint to pop while turning, but bad inner joints will usually manifest as a clunking under acceleration or braking. While turning, the inner wheel pivots at a sharper angle than the outer wheel; so, turning the wheel in the direction of the bad outer CV joint will cause a louder and more violent popping than turning it the other way.
Other possible causes include articulation points in the suspension, like the ball joints, sway bar end links and bushings. But usually, these exhibit a deeper, more metallic tap or knock along with some vibration through the steering wheel or chassis. Bad CV joints will also cause vibration, but it's steadier and not necessarily related to each individual pop.
