Popping noise

I drive a Chevy Venture. When I am backing out and turning the steering wheel, there is a popping noise that seems to come from under the car. The mechanic hears it but doesn’t know what is causing it. I think I need a new mechanic. What could it be?

Knowing the year and mileage might help, but a popping noise could be a badly worn lower ball joint or tie rod end ball socket that is totally devoid of grease.
Dry metal on metal under tremendous pressure can cause several different types of noises and popping is one of them.