I used a mug for tea a few times yesterday and left it sitting on the side after I'd used it. This morning, unable to sleep with the howls of wind, I went down to make a cup of tea in the same mug and rinsed it. Loads of bubbles came out as if it had washing up liquid in it. It hadn't! I thought I had rinsed the mug enough and filled the kettle with it. When the kettle came to boil, bubbles came out of the top! Far too much for 4am! Wtf is happening?!