Things that are concentrated have been gathered together in the smallest possible bunch. If you use a concentrated cleaning product, you might need to mix it with water before using it.
Concentrated often refers to a liquid solution that's very strong, but it can describe anything that's condensed into one area. When you finally clean your bedroom, you’ll have to pick up the clothes that are scattered everywhere so they’re concentrated in the closet. Concentrated can also mean that something is very focused. When your room looks great, it's because you really concentrated on the cleaning.