The art world consists of more than just artists and gallery owners. There are also auction houses—like Christie's, Sotheby's, and Lyon & Turnbull—who put up works of art for sale to the highest bidder. It is from these auctions that you hear about millions of dollars being spent on a particular painting, whether it's a masterpiece or a more obscure work.

Here are 7 of the paintings that earned the most money in auction sales to date.

1. Three Studies of Lucian Freud by Francis Bacon: Although his work is less renowned than the Old Masters or the Impressionists, English painter Francis Bacon has nonetheless kept a strong presence in the modern art market. His triptych painting of fellow artist Lucian Freud was sold for $142 million at Christie's in New York on November 12, 2013.

2. The Scream by Edvard Munch: Being so iconic, this surreal depiction of a tormented man on a bridge at sunset has been the subject of not only the highest auction sales, but also several theft attempts, some of which were successful. At its most recent sale, it was auctioned off at $120 million at Sotheby's in New York on May 2, 2012.

3. Nude, Green Leaves And Bust by Pablo Picasso: Produced by Picasso, this Cubist portrait of his mistress Marie-Therese Walter was kept in the collection of his friend, the art dealer Paul Rosenberg, during World War II until the Brody family purchased it in 1951. The painting was sold for $106 million at Christie's in New York on May 4, 2010.

4. Silver Car Crash (Double Disaster) by Andy Warhol: This double-panel painting from 1963 depicts the wreckage of a car accident and the mangled body of its driver. Warhol used newspaper photos of the incident and recreated them on a canvas with his trademark silk-screen process. It was sold for $105 million at Christie's in New York on November 13, 2013.

5. Boy with a Pipe by Pablo Picasso: As one of his earliest Rose Period paintings, Picasso's depiction of a Parisian boy holding a pipe is a curious glimpse at his style before he delved into the Cubism he's remembered for today. It was sold for $104 million at Sotheby's in New York on May 5, 2004.

6. Dora Maar au Chat by Pablo Picasso: This Cubist painting shows Picasso's lover, Dora Maar, seated in a chair with a cat perched on her shoulder, created with passion and extensive detail. It was sold for $95 million at Sotheby's in New York on May 3, 2006.

7. Portrait of Adele Bloch-Bauer II by Gustav Klimt: Besides being the lovely portrait of the wife of an industrialist who sponsored artists like Klimt, this painting was also subject to theft by the Nazis during World War II. It was held in an Austrian museum until its return to its rightful owner in 2006. Later that year, the painting was sold for $88 million at Christie's in New York on November 8, 2006.

Image by M C Morgan on Flickr