3. When I boil water in the kettle, it makes a nice cup of tea. Sometimes I need to use a microwave because a kettle isn't available. I boil the water in the mug and it looks pretty normal, but when I drop in the teabag the water froths up and looks foamy.hen I boil water in the kettle, it makes a nice cup of tea. Sometimes I need to use a microwave because a kettle isn't available.