That's the way I used to clean after shooting corrosive (that includes using Hopps 9). The next day I would inspect the rifles, and there would be brown fur (rust) growing inside the barrel. Then I would scrub it down again. Again the next day, more brown fur.
It would take me an hour to clean each rifle each time. After the third cleaning, it seemed to take, but a week later, more brown fur.
That cycle stopped after I started using the boiling water down the bore trick after range sessions. One scrub with the brush, two or three patches down the bore, then one oily patch pushed through. No more furry barrels. Now I spend 15 minutes cleaning instead of an hour.
Since I have the bolt out at the time, I pour the water over the bolt head and the gas piston while I'm at it.
Pouring the hot water is enough, OP, no reason to "cook" your rifle.