A Kelly Kettle / Volcano Kettle will boil water in 3 to 5 minutes depending on the fuel you're using. Made from aluminium it is essentially a double-walled chimney with the water contained in the chimney wall. Once the campkettle is filled with water, simply start a very small fire in the base, set the kettle on the base and drop additional fuel (twigs, leaves, grass, paper, etc.) down the chimney.
The large internal surface area of the chimney heats the water very quickly. When the water boils, hold the Handle at an angle of 90° to the Kettle - then lift the Kettle clear of the base.

To pour, lift it by the handle and tilt it using the cork chain.

If additional water is required, simply refill the kettle with water and place it back on the base when the fire is still burning.  Refill the chimney with fuel and you can look forward to a second kettle full of boiling water within a matter of minutes.