Can anyone tell me where can I get a heating coil where u put in the mug to boil water?

I'm looking for a portable water boiler. The one that looks like a heating coil(dual voltage if possible) where you put in a mug to boil some water for cup of tea/coffee. I live in Kuala Lumpur, Malaysia. I search some of the electric appliances shop but fail to get one. If you know what I'm talking about and know where I can buy one, please drop me a note. Thank you.