Water has a specific heat capacity of about 4.2 Kilojoules per kilogram per degree Kelvin, so it would take about 6 Kilowatt Hours of electricity to heat 100 Litres of water from 15 degrees centigrade to 65 degrees centigrade. As a standard immersion heater is 3KW, so it would take 2 hours to heat 100 Litres of water.
A large number of medications may cause hiccups. Medications taken only at bedtime, such as sleep medicine, cause hiccups primarily during sleep. Other medications cause hiccups at other times of the day as well. These are examples of medications that may produce hiccups: Sleep medications: eszopiclone (Lunesta)
   Hiccups are muscle spasms of the diaphragm. They are caused by  irritation of the diaphragm or the phrenic nerve which controls it.  This can be as simple as eating too much (so the stretched stomach  pressed up against the diaphragm) or lung cancer.