This work addresses the semantic evolution of constructions of the llegar y + FV type in Spanish. Taking as a point of departure their characterization as monopredicative structures, we propose that the core meaning they convey is the interruptive aspect, which can develop mirativity as a secondary value. From an empirical point of view, documentary evidence is provided which shows the deeper historical reach of uses marking an event's abrupt occurrence, in contrast to the recent and still sporadic uses to which an unequivocal mirative value can be attributed. From a theoretical point of view, this process of change is formulated as a process of scope increase in the hierarchy of clausal operators, which appears as a common assumption to both functional (Hengeveld 2017) and formalist (Roberts 2012) approaches. Finally, our analysis shows that a single and unified core semantic value, 'abrupt transition', can be suggested to cover all uses of llegar y + FV. This value, depending on the hierarchical level at which it operates, can trigger either an aspectual value -if applied to states of affairs- or a mirative value -if applied to propositions, specifically, the evidence acquisition time- (Carol 2018, Lau y Rooryck 2017).