Last night while I was out driving my coolant light turned on.

I immediately pulled over and checked the coolant level. It looked fine so I started the car back up and the heat was back to the normal 190º. I let the car sit idle for 30 minutes and the temperature stayed at 190º. After the 30 minutes I decided to drive home hoping it was a fluke, 10 minutes into my drive home the car starts to over heat again first hitting 200º then 250º. I pulled over and let the car idle for 5 min and the temperature went back to normal 190º.
It did this over and over.

Any ideas?