GotGarlic
Chef Extraordinaire
Look on the bottom of the container. See if the name is done in metal such as silver or gold.
The metal has to actually be exposed to the microwaves in order for it to cause sparking. I used to use a chrome-rimmed bowl to heat leftovers at work; I covered the bowl with a paper towel and never had a problem.
I'm baffled by the garbanzo issue, though.