Jeep TJ 4.0 Engine overheating

A few days ago, after my 45 minute commute home, I noticed a burping sound after shutting it off. Temp had been normal, but saw the coolant reservoir tube bouncing around with the burping sound. It was a little low, so I added coolant. Wasn't completely empty or anything, about half full. That was on Sunday.

My morning drive to work, I checked the past couple of days and no burping sound, but in the afternoons when it is hotter, I notice it when I get home. Coolant level was fine yesterday afternoon. I did a little research but found this was common in hot environments for the pressure to build and the burping sound in the tube.

This morning, about halfway to work, my check gauges light came on and my temp was approaching redline. I pulled off, let it cool down few minutes, and noticed the fluid in the coolant reservoir had a slight red/pink tint to it. Obviously I'm going to take it to a mechanic today, but just wondering what it could be. The temp would increase quickly, then go back down quickly as well. There were no leaks when I crawled under it, and nothing was steaming out of the radiator or anywhere else in the engine bay.