Caffeine Pills doesn't dissolve in hot tea

I'm drinking Rooibos Vanilla Tea and I like to dissolve an 80 mg caffeine pill in it. I hand press the pills myself from pure caffeine powder. However, the pill doesn't dissolve that good in the tea. Instead, it either brakes into smaller pieces and float around or doesn't dissolve at all.

Is there a creative way to make them dissolve, such as using some sort of binding agent? I already tried to use capsules, but I don't like the idea very much, because you have to open them and pour out the powder.