For what purpose may synchronization primitives and containers from Boost library be needed?

For what purpose may synchronization primitives and containers from Boost library be needed if the project uses C++ 11/14/17 in which there are already containers and synchronization primitives?

I know that Boost.asio is usually used in work with the network, Boost.spirit - usually for parsing of text. Do you know about the usual purpose of the other parts of Boost?

This question is from the C++ interview.