A recipe for cooking pork calls for sake in the marinade. Should I boil the alcohol out or should I marinate with the alcohol intact? I read somewhere that alcohol can cook the meat just like acid, but what I can't figure out is whether that could be beneficial and actually improve the end result.
Unless the recipe specifically directs you to cook the marinade, you should just use it as is.
The only time you would normally cook a marinade is after it is used, in reducing it for use as a sauce—and of course, not all marinades are suitable for such use.