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Rupert's drop

noun
Ru·​pert's drop | \ˈrüpərts-\

Definition of Rupert's drop 

: a congealed blob of glass formed by dropping melted glass into water and setting up such residual stresses that the globule explodes violently when the surface is scratched or a piece broken off

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History and Etymology for Rupert's drop

after Prince Rupert of Germany †1682 who first brought it to England to his uncle Charles I of England

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