What you are experiencing now is the result for not following the corret service interval of coolant, using ordinary water/ no coolant that made serious rust and cavitaton. Next thing to watch out after radiator and gasket failure is water pump damage.

Other collateral damage to watch out are
- Stucked thermostat(worse if it was missing) making your temp erratic. Temp should be within operating temp no matter if you're going fast or slow.
- Leaks on the cooling system(hose, rad cap, warped gasket) thus evaporating fluids. Using ordinary tap water lowers boiling point causing too early opening of your rad cap.
- Trapped air due incorrect bleeding could also make erratic temp and overheating damage.

You should only use distilled/ de-minirelized water with coolant mixture. Ordinary tap water are heavy with minerals that alters acidity, it then corrodes/ cause cavitation when subjected to heat and pressure with dissimilar metal components of the engine.