You can try this. Boil water in a cup, and put a teaspoon of instantaneous coffee in it. I have observed that when you do this, most of the time there is some coffee sticking to the spoon after I empty it in the cup. these particles of cofee form filaments like those that are formed by iron filings in a magnetic field. They stick out from the spoon like if they were being repeled. I have not done this as an experiment but It just happens that I make coffee that way and I usually observe this phenomenon. Now, if this was magnetism, then I would suspect the coffee has been adulterated with some ferromagnetic material. I have not tried doing it with a plastic spoon, which would I guess disprove the magnetic theory if it still happens. Another explanation would be that the moisture from the hot water somehow allows the particles in the coffee to coalesce in a particular way. I have lately been too busy to start doing experiments on this, but maybe some of you guys have the time and can tell us your experience and conclussions on this topic. The nice thing is that it is a cheap experiment.