Mr. Pott was an average man, with an extraordinary skin condition

One day Mr. Pott (legend says his first name was Arthur) went to the doctor to get his skin checked out. He said "Doctor, I have a very odd skin condition. Multiple times a day, my skin will puff up and get all red almost instantly, with no warning."

The doctor thought this was very odd, and wanted to have Mr. Pott wait with him in one of his rooms for a while to see if he could catch the odd phenomenon.

They waited...

And waited...

THERE! No, that was just a trick of the light...

Hours went by...

Finally it was time for the doctor's office to close. Mr. Pott left the office, and as soon as he got into his car, his skin got all red and puffy.

He called the doctor the next day, and said that it happened again as soon as he got into his car, and asked if he could come back into the office. The doctor said sure, since he wasn't busy that day.

Again Mr. Pott and the doctor waited to witness the described symptoms, but again, nothing happened all day.

That night, as Mr. Pott was getting into his car, he broke out in a rash almost instantly.

Mr. Pott again called the doctor and asked to come in.

Every day Mr. Pott would go see the doctor. This went on for days, weeks, and finally months, to no avail.

In fact, the doctor never did see the odd skin condition, because a watched Pott never boils.

Edit: A name