In a heavy saucepan, combine brown sugar, corn syrup and butter . Place over
medium-high heat. Cook, stirring often until sugar dissolves. Continue to boil gently,
without stirring, until a candy thermometer reaches 280 degrees F (syrup separates
into hard, but not brittle, threads when dropped into very cold water).
Remove from heat and stir in rum extract. Pour over popcorn and raisins.