Imagine being on a ship in the middle of the ocean and in every direction you look, there is nothing on the horizon and everything you see is perfectly flat in every direction. Is there any desert (or other terrain) in the world that comes close to giving you that vista on land?
The Nullarbor in Australia might qualify:
(courtesy Nullarbor Roadhouse)
It's a huge, completely flat and virtually uninhabited plain. As the fake Latin name implies, there are "no trees", and there's nothing on the horizon either since there are no mountains nearby. There are, however, some scrubby bushes and grasses, so it's not entirely barren.
In Botswana the Makgadikgadi Pan qualifies, which is one of the largest salt flats in the world.
Lying southeast of the Okavango Delta and surrounded by the Kalahari Desert, Makgadikgadi is technically not a single pan but many pans with sandy desert in between, the largest being the Sua (Sowa), Nwetwe and Nxai Pans. The largest individual pan is about 1,900 sq mi (4,921.0 km2). In comparison, Salar de Uyuni in Bolivia is a single salt flat of 4,100 sq mi (10,619.0 km2), rarely has much water, and is generally claimed to be the world's largest salt pan. A dry salty clay crust most of the year, the pans are seasonally covered with water and grass, and are then a refuge for birds and animals in this very arid part of the world. The climate is hot and dry but with regular annual rains.
There are places like that in Kazakhstan. Check http://welovemountains.net/cycling-east-part-18-aktau-riding-in-kazakhstan-pt1/