George
You probably had a bit more than a 50/50 mix and were abit more antifreeze than 50%
Actaully you can get antifreeze to jell with a strong mix.It still moves but heat transfer is not very good and there is why you had your hot engine symptoms.As you say you cut back enough to solve the problem.I do not mix as to percentage but check as to the freezing point of the mixture.
I like to have a mix that is good for 40 below in C or F degrees.-40 is the same in either C or F
This has never given me a problem.