Coolant Spill

I was filling my radiator with coolant today and I first filled the main radiator to the top, then filled the reserve tank to the max line on the stick. My car had overheated yesterday. After this, I drove around to see if that was the problem and the car overheated again. When I opened the hood, the coolant was spraying out everywhere from the reserve tank. What does this mean?

May have got hot or may have air lock or any number of problems.
Try refilling and bleed the air out of the top of the engine.
Some of them have bleeders and some of them you will have to take a hose or line loose to bleed them.
MT-2500

after u r sure u got the air bubbles out, opt for testing/chaning the radiator cap... it can only hold the required psi rating on the cap & if it's not doing so, car will boil over sooner...

check oil level/condition... if it's black as hershey syrup change it fast.

milky oil? suspect head gasket leak...

you blew your water pump!

you blew your water pump!
Blown water pumps tend to leak like mad or make a clicking/grinding noise when running.
If none of that is happening, IMO your thermostat is stuck closed. These are very cheap and easy to replace.