It is related from Asmaa Bint Abu Bakr (ra) that when she would prepare a broth, she would cover it for some time until it would stop boiling (or until it would no longer be extremely hot). After related this practice, she said, Verily, I heard the Messenger of Allah (saas) say,

Verily doing so allows for a greater degree of Barakah (blessings.) 1

Abu Hurairah (ra) said,  Food should not be eaten until its steam goes away.2 In Zaad Al-Maaad, Ibn Al-Qayyim said that the Prophet (saas) would not eat food while it was intensely hot. And again, Barakah in this context means safety from harm as a result of eating, the nourishment provided by the food, and strength achieved for obeying Allah (swt)

1) Ad-Daarimee related it (2047), and Al-Albaanee included it in his Silsilatus-Saheehah (392). Ahmed related it as well (26418)

2) When grading this Hadeeth in Irwaa Al-Ghaleel, Al-Albaanee said, Saheeh, and Al-Baihaqee related it (7/2580)