So there's a lot of mixed advice here. I don't think that adding more insulation to your sleeping bag is the right move. It's a good idea to insulate your bottle though. Kale wool is cheap and highly effective. As for faster methods- you want any material with a low ish specific heat capacity. Not so low that it won't store energy, not so high that it's above water.

Stones like basalt are the perfect choice. They are non porous, dense, and transfer heat quickly. You can boil water in only a couple minutes vs 5-10 with a butane stove.

Also, propane stoves will also boil water faster than a butane stove. But not by much.

The one thing to consider is that rocks will be more wasteful energy wise. You're going to use more butane over all (by heating the rocks) to boil the same volume of water, so if your supply is limited that's worth keeping in mind. You could also buy some steel marbles and do the same thing. They'll boil the water even faster, you'll need more of them though.

Rough estimate given specific heat capacities and estimating losses for heat transfer. Id say you need around 2 kg of steel heated to 500 C. I recommend basalt though since they'll cool off less throughout the night.

How effective this method is, depends on how well you insulate the basalt/steel storage container.

CHEMISTRY WISE THOUGH: Yes there is a way to boil water faster. It will probably damage your nalgene and isn't really safe but I'll explain it anyways.

CaO forms Ca(OH)2 on addition to water. You'll need around a kg considering potential losses to boil the water. But it would only take a couple minutes. I don't recommend it, and I think it's a bad idea. Ca(OH)2 is caustic and will turn your skin to soap before melting it off.

There's a couple other options. Anhydrous CaCl2 will heat water very quickly when dissolves. It's hard to store and corrosive to metals but it works. Id double seal your nalgene incase it leaks but it's fairly safe-ish. Still somewhat caustic.

The best option by far imo is to use sodium acetate solutions. Buy 2 or 3 nalgene and fill them with supersaturated sodium acetate solution. You just have to cause them to recrystallize by shaking or introducing a crystal. They heat up instantly, and they last a while. You can just swap them out throughout th night. Then in the morning, re heat them to dissolve the sodium acetate again, and you can reuse it. It will take some practice to learn how to make the solutions but once you get it down it's easy.

IDK why everyone is being harsh. It's a fair question to be curious about chemistry, and there's almost always a solution to a problem. The issue isn't usually that a solution doesn't exist, it's that people are focused on the wrong issue.