cooking on a ceramic top (flat) stove

Hello, my wife and I recently purchased one of those stoves with a flat top - i think they are called ceramic top stoves.
I was trying to prepare a recipe on it that called for bringing the goo I was making to a boil and heating to at least 250 degrees. I had a reliable candy thermometer in the goo, and boiled it for at least 15 minutes and i could never get the temperature to get to over 220 degrees.
I live in Colorado, at 6,200 feet and I don’t know if that has anything to do with it, or if it is this type of stovetop that just can’t get that hot. Anyone ever have a similar problem with this type of stove?
(i tried every burner, same result, so i know its not an individual burner issue).

I have a ceramic cook top and find that I have to lock the burner to keep it from cutting off before it gets hot enough to deep fry.

I had one till I moved, and I loved it.!!! . Wish I had one here in this tiny apartment.