This is an irregular verb. It is a model verb.
PresentPresente
El agua bulle en la olla grande.
The water is boiling in the big pot.
ImperfectPretérito imperfecto
La sopa bullía mientras poníamos la mesa.
The soup was boiling while we set the table.
FutureFuturo
El caldo bullirá en unos minutos.
The broth will boil in a few minutes.