i researched online and all i could find that if blood is mixed with other things than it will evaporate out of it leaving the other substance behind such as if mixed with soda, water, or even solids such as gums that are very malliable. i could not find anything on why blood dosent evaporate on its own though. just a thought no proof to back this up though i feel that when the cells in your blood die when coming into contact with the air they secreate some type of substance to form a "shield" to try to protect the other blood cells that they may be covering. sorry that i couldnt find any hard evidence for you.
In a sense it does, you lose intracellular and interstitial fluid when you sweat….when you are dehydrated, the ratio of cells to plasma increases…and you’re blood is very thick because of the fluid loss.
