Basements, Attics and Crawl Spaces - Dry-Lock Issues

I recently bought a house with an unfinished basement, and am planning on finishing it out over the next 2 years. The house was built in 1988 using concrete block as the foundation. The foundation rises above the ground about 3 feet. It appears the previous owners put 1 coat of Dry-Lock on the basement floor and walls. I want to add 2 more coats. Here is my problem. There are patches of a substance on the walls and I am not sure what it is. When I use a scraper and remove some of it, it has a spongy texture to it. It is only slightly discolored in some places. I do not believe it is due to water leakage, since I have been here several months and have not seen any. It may have been mold when the first coat of Dry-Lock was applied. Should I spend the time to remove it, or simply apply the 2 additional coats over it? Are there any issues with removal? Any help would be greatly appreciated.

Welcome to the forums! What you are seeing is effervescence, which is a forming of a gas from a liquid or solid causing the surface to be released. You will need to wire brush down the entire wall area to get rid of the loose stuff and re apply the dry loc.