From what I've learned so far, it takes several hours of boiling. The ratio of initial sap to final syrup is 30to40 to 1. So for instance, 30 liters of sap would need to be boiled down until it nets only 1 liter of syrup.

After chatting with him today, he tells me he was just doing the final boil stage indoors where you transfer the dwindling amount to a smaller pot. It would be difficult to do the full boil process indoors (crock pot) as you have hours of heavy steam in your kitchen.

With great power comes Awesome irresponsibility.