If you have not already done so, download Avogadro for free and watch the tutorials if necessary.
One of methods of decafeinizing cofee beans is to treat them with water. How does water dissolve caffeine?
Open Avogadro and import the caffeine molecule (sequence File→ import→ fetch by chemical name), then start the optimization (sequence click E→ check that is Force field MMFF94) and add water molecules around caffeine structure.
What do you see forming? Could that be the mechanism by which caffeine is dissolved and on which one of methods of decafeinization is based?