If the input water is municipal water, then it contains minerals,
which will deposit out as boiler scale within the device, changing its
temperature flow characteristics and internal geometry -- for
instance, partially blocking and thus constricting the smallest outlet
diameter, increasing the resistance to water flow, increasing the
internal water/steam pressure within the device, causing increases of
temperatures both of water and also of the heater resistor deep within
the device, along with the mass of metals, storing increased heat
energy in materials at various locations and temperatures -- if the
heating resistor starts to deteriorate from overheating and corrosion,
developing cracks, then it can short out the input electric voltage,
electrolyzing the water into H2 and O2 bubbles, and causing many other
complex electrochemical reactions with the impurities and dissolved
metals in the water at various locations, temperatures, and pressures
within the "witch's cauldron" -- eventually runaway short circuits can
destroy the heater resistor and explode the device...
