Yeah, boiling in a flask is like playing chicken.
Here's a trick I started doing lately when making bigger starters (maybe not so tricky to some, but it has helped me):
I boil 3/4 of the water i need directly in the flask a day before I need to make a starter. after it's boiled for 15 min or so, I cap it with foil and let it cool down on the counter and then eventually, it goes in the fridge.
The next day, I boil a super concentrated (4x) wort with a little over 1/4 of the planned volume. Boil for fifteen minutes, then cover and let it cool down on the stove. Once its cool enough - say about 150df or so, I pull the flask from the previous day holding just water, and direct pour the wort in and its usually right at 60df or so! Put in a sanitized stir bar and its off and running.
Just thought that may help some of you out there.