All supermarkets have them, right? Go to a bigger supermarket, but there are usually no small supermarkets.

Boiling milk tea only learned a trick from TV yesterday:

Put the cream into the pot, melt it, add the milk, and add the tea when the milk temperature reaches about 80 degrees. It is best to use Tieguanyin. What kind of tea I want to use should be no problem. Then the tea leaves in the pot unfold, which means that your milk tea will be cooked soon, and it won't take long.

I hope it helps you.