1991 Ford Taurus GL 3.0 V6 steering cut out

Hello, I own a 91 taurus gl, and as I was driving to a restaurant last night, I heard a loud pop like something either snapped, or popped out of place. Then I tried to turn my wheel and I found that it had become very difficult. It appears that my power steering pump is still finctioning, and has fluid. As I try to turn the wheel it is difficult, and hangs in certain places. It makes a popping sound as I turn the wheel as well, and the sound seems to be coming from in front of my firewall. I am uncertain if it might be my rack and pinion, or if it might have something to do with my power steering pump, or my wheels, or whatever. Please help!