#3: Limelight

Limelight – meaning "the center of public attention" – began as a dazzling and dangerous special effect.

In the early 19th century, a scientist discovered that forcing a combination of oxygen and hydrogen through a pipe to ignite a lump of hot limestone (quicklime) created a brilliant illumination.

After another engineer refined that technique, the resulting limelight soon appeared on stages worldwide as an early spotlight on individual performers. But the brilliance of the limelight was matched by its danger: it was highly flammable.

By the end of the 19th century, limelight faded from literal center stage but kept its figurative "center stage" meaning.