I thought it was nearly impossible to see an alcohol flame. I remember this from watching dragsters running on alcohol.
I've never heard of this either, when you get a bubble to form on the dough it will contain some alcohol, but it will also contain a good portion of vaporized water too.
I've seen this happen when someone didn't set their oven to a temperature below the flash point of oil (about 435F) when seasoning pans, what happens then is the oven fills with smoke, lots of it, and when the door is opened, POOF! Your share of excitement for the week all in just a second or two. Before the days of fail safe pilot light gas valves, I once had an oven go out on me, I opened the door to vent the gas and hit the ignition switch, The oven was not fully ventilated, the spark ignited the gas, and the following explosion, resulting in a large yellow fire ball, blew the door off of the oven and removed my eyebrows as well as ignited the paper cap I was wearing. Shortly after that the oven was fitted with the latest gas safety devices.
Tom Lehmann/The Dough Doctor