High coolant temperature

Finished doing a valve cover gasket job drove it to get some gas and all of a sudden, the temperature gauge jumped from where it should be around 80-100c to a full gauge and a red message appeared stating coolant off, turn engine off. I don't see any leaks. I washed the motor before I drove it and spent 30 minutes cleaning the inside while the car was running. First time to see it do that. Scanned it and temperature was 248f for ECT. Upper and lower radiator hoses are not so tight and normal heat. Once you turn the car off and on again the temperature gauge goes to middle again but scanner shows 230f or so and climbs to around 245. Also, once car reaches optimum temperature fan stays on high, even while driving. Checked sensor under the reservoir and it's okay. The reservation also feels cool, not as hot as it should be. If I rev up the motor scanner, it shows temperature goes to 250f. Gauge climbing slowly to above where it should be, 120c or so.

Also, once I turned it off, I felt an upper hose and I can feel the water booing inside it but it's not very hard, normal. Opened reservoir cap and it was boiling and shot water off, then I closed it.