My favorite stove is the Jetboil Sol Ti. With no fuel, it weighs 284g; with a mini isobutane canister (100g of fuel) it weighs 452g.
Being built with an absolute minimum of materials, this stove is intentionally constructed to be sufficient for one job: boiling water. When full of water, the metal components of the stove should never greatly exceed 100 degrees (C), since all of the burner’s energy is going to heat the liquid water.
Being alpinists, however, we often don’t have the luxury of liquid water. Melting snow is an essential part of climbing in the mountains, and we want to use the lightest possible tool to accomplish this task.
The pictoral warnings on the side of the Jetboil explicitly instruct us NOT to melt snow or ice with the stove. This is because snow can undergo a phase change from solid directly to vapor (sublimation). In a JB full of snow, an empty cavity can form in the bottom of the cup from where the snow has sublimated away, leaving the full fury of the burner to heat the stove well past its safe operating temperature. Quickly, the delicate metal heat-exchanger mounted to the bottom of the cup will melt. Now, instead of liquid water, you have drops of liquid titanium (not ideal).
SO, when attempting to melt snow in a Jetboil, it’s important to accumulate some liquid water as quickly as possible. You could do this by saving a bit of liquid water in your bottle, and using it as a “starter” for each new batch of snowmelt. You could also put a bit of snow in your water bottle and stash it inside your jacket before climbing, using excess body heat to melt it.
But, if you’ve done none of these things, and still want to melt snow, there is a way. Simply put a thin layer of snow, as light as you can find, in the bottom of the JB cup. Keeping the cup off the burner, light the stove and turn the flame to low. Hold the cup 1-2 cm above the flame and shake it, as if you’re sauteing a stir-fry. As the snow melts to liquid, add another handful. Once you’ve accumulated enough water to fully cover the bottom of the cup, you can attach the cup to the burner as normal. Continue to add snow slowly, and stir it frequently with whatever utensil is handy (spork, nut tool, piton, etc). After you’ve melted ~200mL, fill the whole cup with snow, pack it down, put on the lid, and turn the burner to high.
If you’re making multiple batches, always leave at least 100mL in the JB, pouring the excess liquid into a bottle and adding more snow constantly.
As a final note, Jetboil includes a handy plastic cup on the bottom of the stoves, and this is a good tool for scooping snow. When cold, though, the plastic become quite brittle and I’ve had more than one shatter. A few wraps of duct tape will reinforce the cup, as well as provide some insulation!