The hottest places on the planet make us think of deserts. Vast spaces, full of sand and baking heat that drives everyone into hiding, and are potentially dangerous to most forms of life. Although deserts are amongst the hottest places, they aren't alone in being the hottest spots on the planet.
The hottest place on the planet, with the highest ever recorded temperature is El Aziza (also known as Al Aziziyah) in Libya. A temperature of 136F was recorded there on September 13th 1922.
Death Valley in California managed a close second. On July 10th 1913, the temperature in Death Valley reached 134F.
For the highest average temperature, we have to move to Ethiopia, specifically to Dakol, located in the Danakil Depression. The average temperature in Dakol is 94F.
If we want to be really scientific about this and include the whole Earth, we should consider our insides too. Although no-one has yet accurately gauged these temperatures, scientists believe that, as you move closer to the center of the Earth, the following temperatures are likely.
The Mantle - Roughly 870C (1598F)
The Outer Core - Around 4,400 to 6,100C (7952 to 11012F)
The Inner Core - Around 7,000C (12632F)
If you want to be pedantic about it, the hottest spot on Earth is actually inside, but let's return to the surface.
The reason for certain areas having such extremes of temperature are due to a number of factors. Areas that have very dry soil and low rainfall, deserts being a perfect example, are prone to high temperatures. Because there is little to no humidity, the sun can cause extremes in temperature, and most desert regions have twice the solar radiation compared to regions with higher humidity.
The average annual temperature for a desert region is around 20-25C (68-77F) but extremes are common, some places averaging around 43.5-49C (110-120F). Deserts are extreme at night too. Average nighttime desert temperatures can fall as low as -18C (0F).
Another factor in extremely high temperatures relates to location. If an area is in a depression, like Dakol, or at low altitude, like Death Valley, it is likely to suffer high temperatures. This is due to air flow. Cool air rises and equally, warm air moves down. In a depression or at low altitudes, warm air collects together and gradually descends. The lower it goes, the warmer it gets and so the surrounding area is caught under a layer of warm air which increases the average temperature. There is a far more technical explanation given at this link.
Wind is also a factor. We have all felt the cooling effects of a breeze on a hot day. If a region is prone to being windy or having regular winds, it is far less likely to suffer extremely high temperatures. Wind moves the air around and cools the air temperature. This doesn't allow for heat to build up to extremes.
More information about extreme temperatures can be found in this list. So, if you want to live somewhere with ridiculously hot temperatures, Dakol is your best bet for constantly scorching heat. Other than that, move to somewhere that is at low altitudes, very dry and never windy. More information about the hottest places on Earth can be found at the links within the article.