The boss was cheated out of a sum of money and was absolutely livid.
Tips
history
Earliest known use is in the Qing-dynasty novel 《廿载繁华梦》 (Niànzǎi Fánhuá Mèng, 'Twenty Years of a Splendid Dream') by 黄小配 (Huáng Xiǎopèi), where a character is so enraged that smoke seems to pour from her face before she coughs blood.
memory
七窍 (qīqiào) = the seven openings of the head: 2 eyes, 2 ears, 2 nostrils, 1 mouth. Picture anger so intense steam blasts out of every single one of them.