Was trying all possible ways, but never succeeded:
The provided solutions do resolve the issue. However, they also impact all other textarea elements with the same styling. I had to solve this and just created a more specific selector. Here is what I came up with to prevent invasive changes.
.modal-content textarea.form-control {
max-width: 100%;
}
While this selector may seem aggressive. It helps restrain the textarea into the content area of the modal itself.
Additionally, the min-width solution presented, above, works with basic bootstrap modals, though I had issues when using it with angular-ui-bootstrap modals.