U can Consult any Oral Medicine specialist regarding this to get accurate Daignosis and treatment plan if required.

I would require an image to be clear about your situation as it can be tooth related or probably due to some trauma that might have caused. Please provide with images.

It might  be anything . Post clinical photo. If it's due hot food or liquid should resolve on it's own in 7-10 days. Else consult oral surgeon

Do post a picture of it.

Is it at the palatal region..? I.e roof of mouth. if so, can be due to consumption of hot and spicy food intake. Chronic Cigeratte smoking(minor salivary gland inflammation) at palatal region. A reference of clinical picture of your mouth would help in diagnosing specifically. Pls take a snap of the area in question (inside your mouth). It is nothing very serious.just avoid hot and spicy food. May not eliminate but it won't be harmful in any way.

Bump on d gums is usually due to infection.. Hot water won't cause u bump.

An image will give us a better idea ...is the bump at the gum area or inner cheek ? Drinking warm water would not cause any bumps normally , but as I say if you are drinking “ hot “water it’s not good for your inner mouth and throat it will scald it and may cause water retained boil .