What does crust and sugar over like a syrupy sweet mean Dream deferred?

The phrase "crust and sugar over like a syrupy sweet" from Langston Hughes's poem "Harlem" suggests that unfulfilled dreams can become superficial and overly sweetened, masking their bitterness. It implies that when aspirations are neglected, they may form a hardened exterior, concealing the pain and disappointment underneath. This imagery emphasizes the idea that deferred dreams can lead to stagnation and a loss of authenticity, ultimately transforming potential into something hollow and artificial.