Like yourself, I despise how instant cocoa mix lumps up. No matter how hot the water, no matter how vigorously stirred, those lumps bubble up like so much flotsam. This morning, clearly possessing no other problems, I decided to remedy this once and for all. I dare say no woman would have tried this technique, for reasons that will be clear in the next sentence.
Reaching around my immersible blender, I grabbed a metal martini shaker.
I filled the shaker with boiling water, added the cocoa, and affixed the shaker's top. Now, I know what you're thinking. I thought it too. Which is why I was putting a silicone pot holder on my hand when the steam inside the martini shaker built up sufficient pressure to blow the lid and lacerate the air in all directions with boiling chocolate napalm.
Still hurts.