Mod Box Question...

This is a question on functionality when you are reading watts.
I have a COV Volt Mini that I am cutting my teeth on for mod boxes.
I wired it up to a halogen bulb to get an ohms reading.
What do you suppose happened?

I am using a 35W halogen bulb.
It reads ~0.4ohms cold.
I hit the button and it glows.
I hit the button again and it glows much brighter and the ohms now read 1 ohm.
I can keep doing this until it hits 3 ohms and major brightness.
All while limiting output to 20W.
That doesn't...

Mod Box Question...