Thanks for all the responses.
This is what I have found out. I jacked the front of the jeep up and put the front end(front tires off the ground) up on jackstands. I started the jeep and turned the wheel all the way to the left, where I can manually get it to make the popping noise when I slowly drive it forward or reverse. I got underneath and turned the front tire forward and backwards all the while watching the universal joint within the yoke. I did not hear any popping noise. I did notice some surface rust on the universal joint caps after I scraped some of the road grime off with a small screw driver. On the driver side there is a plastic cover that is suppose to be butted up against the axle housing. It is located close to the ball joint right where the axle comes out of the axle housing. It actually goes around the axle. The plastic cover was not flush with the housing. There was approximately a 1/4 inch gap. I shined a flashlight inside and could see rust on the axle shaft. It was also a little wet where the axle comes out of the housing. The drivers side universal joint had a pin-hole size grease fitting that was covered with crap. Everything looked and sounded like it was working correctly with the exception of what I described above.
The passenger side did not have a grease fitting. Its plasic cover was butted up against the axle housing. I did not see any rust on the axle on that side or any wetness coming out of the axle housing. There was also some surface rust on the caps and joints on that side also but when I turned the wheel forward and backward, it also appeared the work ok.
Sorry for being so long winded on this. I am ready to fix this now.
What should I do now other than bringing it to a shop?
One thing I have not mentioned. This jeep was a sheriffs vehicle a year or so go. I have only had it for a few months and put abourt 20K miles on it.