If you think a great deal of thoughts to which you never give voice, then it will boil over in time.
If your mind is calm and quiet, however, what's going to boil over?
"In-&-out breaths are bodily; these are things tied up with the body. That's why in-&-out breaths are bodily fabrications. Having first directed one's thoughts and made an evaluation, one then breaks out into speech. That's why directed thought & evaluation are verbal fabrications. Perceptions & feelings are mental; these are things tied up with the mind. That's why perceptions & feelings are mental fabrications."
Furthermore, with the stilling of directed thoughts & evaluations, he enters and remains in the second jhana: rapture and pleasure born of composure, unification of awareness free from directed thought and evaluation — internal assurance. He permeates and pervades, suffuses and fills this very body with the rapture and pleasure born of composure. There is nothing of his entire body unpervaded by rapture and pleasure born of composure.
This is the second jhana, the "noble silence".
Train your mind to be still, then there is little left that might boil over.
Gifts he left behind
34. DIDN'T THINK OF THAT
In one of Luang Pu's branch meditation monasteries there lived a group of five or six monks who wanted to be especially strict in their practice, so they made a vow not to talk throughout the Rains Retreat. In other words, no word would come out of their mouths except for the daily chanting and the bi-weekly Patimokkha chant. After the end of the Rains they came to pay their respects to Luang Pu and told him of their strict practice: In addition to their other duties, they were also able to stop speaking for the entire Rains.
Luang Pu smiled a bit and said,
"That's pretty good. When there's no speaking, then no faults are committed by way of speech. But when you say that you stopped speaking, that simply can't be. Only the noble ones who enter the refined attainment of cessation, where feeling and perception stop, are able to stop speaking. Aside from them, everyone's speaking all day and all night long. And especially those who vow not to speak: They talk more than anyone else, simply that they don't make a sound that others can hear."
He defines speech a little differently. But good to keep in mind; esp that last bit in reference to your OP.