Harry Krause wrote in message ...
Sometimes when using the microwave on the boat to boil water, the water
turns 'nukular.'

That is, when I take the coffee cup out of the microwave, and spoon some
instant coffee into it, the water "boils up" and overflows the cup.

This occurs maybe one time out of 20, but when it does, it makes a mess.
I typically fill the cup to the same level with jug water (no one should
drink water stored in a boat's water tanks!), use the two minute setting
on the microwave to boil it, and put in the same super teaspoon amount
of coffee.

What's going on here?

You need to be very careful with that method. Water in a cup, placed
in a microwave, can super heat, because of the slick sides of the cup,
the water doesn't boil until something breaks surface tension. There
are many instances of someone taking a cup of water out of a
microwave, and as soon as a spoon or something hits it, it violently
explodes, right in people's faces and bodies, causing severe burns.